[ci skip] Update CHANGELOG.md

Author: yhatt

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## [Unreleased]
 
+### Changed
+
+- Upgrade Marpit to [v1.6.4](https://github.com/marp-team/marpit/releases/v1.6.4) ([#210](https://github.com/marp-team/marp-core/pull/210))
+- Upgrade dependent packages to the latest version ([#210](https://github.com/marp-team/marp-core/pull/210))
+
 ## v1.4.0 - 2020-12-05
 
 ### Breaking